OS Round Robin C Program

Operating Systems Lab Manual / OS Round Robin C Program

Program Name	Write a C Program for CPU scheduling algorithm Round Robin
Theory	In Round Robin the processor time is shared amoung all the processes and the shared processor time is called as time slice. No. of time slice for process (n) = burst time process (n)/time slice Waiting time for process (n) = waiting time of process(n-1)+ burst time of process(n-1 ) + the time difference in getting the CPU from process (n-1) Turnaround time for process(n) = waiting time of process(n) + burst time of process(n) + the time difference in getting CPU from process(n). Average waiting time = Total waiting Time / Number of process Average Turnaround time = Total Turnaround Time / Number of process Step
Program	#include<stdio.h> void main() { int i,j,n,bu[10],wa[10],tat[10],t,ct[10],max; float awt=0,att=0,temp=0; printf("Enter number of processes: "); scanf("%d",&n); for(i=0;i<n;i++) { printf("\nEnter Burst Time for process %d = ", i+1); scanf("%d",&bu[i]); ct[i]=bu[i]; } printf("\nEnter Time slice size: "); scanf("%d",&t); max=bu[0]; for(i=1;i<n;i++) if(max<bu[i]) max=bu[i]; for(j=0;j<(max/t)+1;j++) for(i=0;i<n;i++) if(bu[i]!=0) if(bu[i]<=t) { tat[i]=temp+bu[i]; temp=temp+bu[i]; bu[i]=0; } else { bu[i]=bu[i]-t; temp=temp+t; } for(i=0;i<n;i++) { wa[i]=tat[i]- ct[i]; att+=tat[i]; awt+=wa[i];} printf("\nThe Average Turnaround time: %f",att/n); printf("\nThe Average Waiting time: %f ",awt/n); printf("\n\t Process \t Burst Time \t Waiting Time \t Turn Around Time\n"); for(i=0;i<n;i++) printf("\t%d \t %d \t\t %d \t\t %d \n",i+1,ct[i],wa[i],tat[i]); }
Input	Enter number of processes: 3 Enter Burst Time for process 1 = 24 Enter Burst Time for process 2 = 3 Enter Burst Time for process 3 = 3 Enter Time slice size: 3
Output	The Average Turnaround time: 15.000000 The Average Waiting time: 5.000000 Process Burst Time Waiting Time Turn Around Time 1 24 6 30 2 3 3 6 3 3 6 9

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